Safety-lamp



W. PRATT.

- Lamp.

Patented Nov. 24, 1857-.

N. PETERS. Phokrlmlosrlpkltv, wamin um. D. c.

UNITED STATES PATENT OFFICE.

WILLIAM PRATT, OF BALTIMORE, MARYLAND.

SAFETY-LAMP.

Specification of Letters Patent No. 18,704, dated November 24, 1857.

To all whom it may concern:

Be it known that I, WILLIAM PRATT, of the city of Baltimore and State ofMaryland, have invented certain improvements in vessels used in holding,pouring, and burning inflammable liquids, as alcohol, spirits, and thevarious hydrocarbon liquids used in illumination, the object of whichinvention is to render all such vessels safe from explosion whenaccidentally ignited; and to enable others to make and safely use myinvention I give a general and particular description, illustrated bythe drawings and letters of reference, which form a part of myspecification.

General description-J form the orifices of reception and delivery in allvessels used for the above named purposes in such a manner as shall makethem practically to consist of a cluster of fine tubes of great lengthas compared with their diameter, so that they may be made soeconomically as to allow of general use, to have sufficient substance torapidly conduct ofl the heat of a flame kindled upon their orificeswithout igniting the inflammable matter contained within the vessel, orimpairing the protective power of the attachment by burning or meltingthe solder which confines it in its place. And at the same time to allowfreely pouring the liquids through, and not become inoperative from thegumming up of the interspaces by the resinous matter which is containedin most burning fluids. And in order to carry out all these requirementswithout the labor and expense of making a cluster of separate smalltubes which would have the same effect, I fill the orifices whichreceive and deliver the liquids, with a volute of metal, so made that itfulfils all the before mentioned conditions. lVe now come to the vesselsused in burning these liquids, for the latter are not safe unless usedin conjunction with the protected vessels for holding and pouring. Froma record of the published accidents which from time to time appeared, Ifound them attributable to three several principal causes. First, theexplo' sion of the filling can, or lamp, or both, by attempting to fillthe lamp, while burning, showing conclusively that both vessels must beprotected. Secondly, the spontaneous explosion of the lamp from theaccumulation of gas in its top, which gas is always generated after thelamp has been a little while lighted, and which is very rapidly evolvedwhen it is in a heated room. Thirdly, the explosion of the lamp from thedropping of the wick from the wick tube on accidentally jarring thelamp, especially where the wick does not quite tightly fill the tube. Ifound it necessary, therefore, to a complete system of safety, not onlyto protect the filling vessel, but to provide against all thesecontingencies in the lamp. I therefore construct the lamp with aprotective orifice to receive the inflammable liquid, and by suitabledevices to prevent the wick tube cap from being accidentally orinadvertently taken off, until the protected orifice is first uncovered;

.to remove or conduct off the accumulating gas in the top of the lamp asfast as generated, and without loss of illuminating power in the liquid;and also to prevent the dropping of the wicks from their tubes onaccidentally jarring the lamp; and again to prevent so large a quantityof the fluid from running out if the lamp should be accidentallyoverturned while the cap of the protected orifice is removed, and to dothis I generally construct my lamp as follows. A side feeder is placedin the lamp in such position relatively to wick tube cap, that theperipheries of the two caps shall intersect; the cap of the feederfitting into a reicess in the wick tube cap, or abutting against a stoside eeder reaches nearly to the bottom of the lamp, inclining towardits center, which arrangement prevents any large quality of projectingfrom it. The tube of the liquid from being spilled or upsetting thelamp. The orifice of the side feeder is filled with the volute fromabout one quarter of an inch below its cap, extending downward fromthree quarters to one inch; through this the lamp may be filled withperfect safety, for if both lamp and feeder or can accidentally ignite,a harmless flame is the only result, and the liquid may still be pouredthrough this flame without the least danger of an explosion, and if thisis left to itself it soon expires of its own accord. To prevent theaccumulation of gas in the top of the lamp without loss of theilluminating product, I make a small tube by the side of the wick tuberunning through the cap and terminating at the flame of the wick. Thistube serves also the double purpose of allowing the lamp to be filledwhen the liquid rises above the lower end of the side feeder tube bypermitting the escape of the air. A small spring or coil of wiresoldered to the under side of the wick tube cap with the coil or helixdirectly under the tube, through which the wick is drawn, effectuallypre vents the dropping of the wick or jarring the lamp.

Description of the d7'awings.Figure 1 represents the top of a commonmetal lamp, in side perspective, A, A, being the body of the lamp, B thecentral or wick cap, containing the wick tubes C, O, and the side tubesE, E, for conducting off the gas, and allowing the escape of air onfilling. The wick tubes are of ordinary size. The side tubes E E areabout of an inch internal diameter. D, is the screw cap of the sidefeeder, and the drawing shows the intersection of the two caps in theirperipheries, to prevent the accidental unscrewing of the wick cap, andthereby exposing the unprotected orifice which is covered by it.

Fig. 2, shows the lamp in section H,H, the side feeder tube, thediameter of which should be from to g of an inch. The volute is placed alittle way down from the top of the tube, as shown in the drawing. Grepresents this volute and its proper position in the tube. F F are thewicks. The other parts being the same as in Fig. 1, it is not deemednecessary to describe them more particularly. H

Fig. 3, is a view of the top of the lamp, showing the relative positionof the parts, marked with the same letters as in Fig. 1.

Fig.4, shows a can or filling vessel onethird the actual size. A, A, thebody'of the can, B the feeding nozzle, G, the handle, Gr, G, the volutesor safety attachments at the orifices of reception and delivery. E is abrace running from the spout to the body of the can. The orifices G Gshould be about one inch for the larger, and of an inch for the smallerone. J is a tube about of an inch diameter in the closed end of thenozzle to prevent dripping.

Fig. 5, shows in top section the orifice of the side feeder tube andvolute, as I prefer to make it. I take any suitable thin sheet metal, astin plate, copper, zinc, brass or Muntzs metal, and pass a strip aboutone inch in width through a pair of toothed rollers, the teeth meshinginto each other, or between dies with teeth raised upon their surfaces.The corrugations should be about one twentieth or one thirtieth of aninch in width and depth. With the piece of metal thus rolled or stampedI place a strip of the same width of plain metal; laying their endstogether, I solder them to a small brass wire or tube and roll themtightly upon the wire or tube till a volute of sufiicientsize to fillthe orifice for which they are intended shall be formed. This is cut offand slipped into the tube'and then soldered, and however long a flameaccidentally kindled upon the melt the solder, burn the volute, orignite the combustible matter within the vessel.

Fig. 6, represents a strip of plain and a strip of corrugated metalsoldered to the wire preparatory to winding them into form.

Fig. 7, shows the edges of the plain and corrugated strips, and how theyform tubes when laid closely together.

Fig. 8, represents a wick tube cap or section, with the helical springsoldered to its under side, to prevent the jarring of the lamp fromthrowing the wick from its tube.

General remarks.In constructing these various appliances for the safetyof vessels used in the purposes above described I do not confine myselfin every particular to the exact details'as shown in the drawings andspecifications, for it is obvious that the results may be attained bymeans which though not identical are analogous, and strictlyequivalentsbut I have shownthat which I consider to be the best and mostsimple method of producing the desired effects. For instance a volute ofplain metal not very tightly wrapped would be safe, but the folds wouldbe liable to derangement, and they will not allow the liquids to runthrough so freely and would easily become clogged by gumming; or asingle strip of corrugated metal wound around itself would formsufficient protection, but the corrugations in some parts will sink intoeach other and in other portions would by the raised parts fallingtogether form the tubes of too large a size. Again, the metal formingthe volute may be made thicker, and ribs raised upon its surface andthis rolled up forming a channeled protection, or still again, thevolute may be formed by winding a fine wire around a small central arborin the form of a helix and when a coil of su'fiicient length has beenformed to fill the orifice, and this coil and so on till a volute ofsufiicient size has been found to fill the orifice, and this thoughlikewise protective, is still liable to the objection of not permittingso free a passage of the liquids through it, and also the defect ofgumming and becoming partially inoperative. But I have found fromexperiment that the method of making the volute of one strip of plain,and one strip of corrugated metal, to be the most economical and onewhich has no practicable objections.

In the arrangement'of the feeder and wick caps the peripheries of thetwo instead of intersecting, may be placed farther apart; and a stopupon the central cap, abutting against the side feeder cap, when bothare tightly screwed down, will prevent the accidental explosion of theunprotected orifice. Another method of arranging these parts would be toplace the volute and its cap upon the central or wick tube cap, leavingthe tube of the volute about% of an inch above the surface of the cap, aring fitted around this part of the tube with a pin projecting from itsunder side sufficiently long to reach through a hole in the edge of thewick cap, and to abut against a stop soldered to the main body of thelamp, so placed that this hole shall be just past the stop when screwedtightly down, would, by being confined in place by the feeder tube cap,prevent the exposure of the central orifice either through ignorance orcarelessness. Another arrangement of the parts is to make the centralcap to consist of two screws fitting concentrically into each other, andinto the top of the lamp. The wick cap is provided with a long cylindersufficiently large to contain the wicks, the cylinder sliding up anddown in the center of the volute, which in this case is wound around thewick cylinder, and fills the space between it and the circumference ofthe screw which fits the lamp topthe lamp to be filled by raising up theupper cap and screw with its cylinder, sufficiently high to pour theliquid through the volute. I have tried all these plans but have foundnone so simple as that which I have particularly described, and shown inthe drawings.

The application of the safety attachment to vessels holding largequantities of inflammable liquids, from which it is exposed by drawingtherefrom with lamp or candle lights, is very simply made by attaching atube containing a volute of larger section than the orifice of the stopcock, so that when soldered upon it, it shall not impede the freedelivery of the contents of the vessel.

I do not claim to be the originator of a safety attachment to vesselsusing explosive and inflammable substances, for many devices to this endhave already appeared, as Newells safety wire gauze tubes, tubes of tincovered with wire gauze, chambers of perforated tin, and cylinders ofthe same, filling vessels with shot, or pumice stone, or sponge, all ofwhich in practice have been found defective. I claim superiority overall. First in simplicity and durability of structure and economy ofmanufacture. Secondly, the great body of metal in my device preventsdeterioration by corrosion, destruction by heat, or the melting of thesolder which holds it in place, all of which I have seen in the wiregauze attachments, the meshes of which to be safe must be necessarilyfine, and these act as capillaries in conducting the fluid to thesurface, which if accidentally ignited burns with a fierce hot flame,destructive of the gauzethe same cause also causes its deterioration bycorrosion or renders it inoperative from gumming up if suffered to be alittle season.

in disuse, preventing thereby the pouring of the liquid through it.

I am also aware that a perforation in the lamp cap for allowing theescape of the accumulating gas, has before been made, but while thisinvolves a loss of from 15 to 20 per cent. of the illuminating liquidmine is equally safe, and applies the gas to the support and increasedbrilliancy of the flame.

I am aware also that Mr. Hemming applied to the oxyhydrogen or compoundblow pipe packages of wire in a long tube and tightly wedged therein;the conducting power of the metallic channels preventing the passage offlame through them; and in my early experiments I tried the same device,but found the practical defects so great as to render it useless for mypurposes. First the wires presented so much solid material in proportionto the interspaces between them, that liquids only slowly percolatedthrough instead of running freely through them, especially after a shortperiod of disuse when they became fouled or gummed up. I tried loosepackages of wire but they were unsafe from dropping out. I then twistedthem but found that although it decreased or obviated the latter defect,it made greater the first one, that of freely pouring through them. Wiregauze has been applied to cases, but the same defects, arising fromburning of the meshes, melting of the solder, corrosion of the gauze,and fouling or gumming up from resinous matter, obtains in thisapplication as well as in the lamps.

I am aware of the existence of Nickols safety valve can but it difiersso entirely from mine that I will only remark that while his devicerequires some degree of presence of mind in the person exposed, mine asa principle of safety is inherent in the method of construction andarrangement, for if both lamp and can accidentally ignite, no explosioncan take place; and a feeble and manageable flame through which theliquid may be still and safely poured is the only result.

I have discussed this subject more fully perhaps than the law requiresto set forth the nature of the invention. But the great number ofterrible and fatal accidents which have taken place, and which no amountof warning seems to lessen, has prompted me to explain the whole matterclearly and thoroughly in order that all inflammable liquids may be assafely used as possible. While therefore I do not claim any of thedevices of others which I have referred to in the foregoingspecifications, or profess to be the discoverer of any of theprinciples, involved is my own devices, (separately considered) I doclaim specifically as follows in accordance with the title of theinvention and foregoing descriptions is illustrated by the drawings.

tal obstructions 1. claim protecting the orifices of ves-:

sels, used in holding, pouring, and burning inflammable liquids, with avolute of ribbed metal wound upon itself; or made of strips of plain andcorrugated metal wound togetherthese so formed making most economicallya series of regular tubes, of great stability and conducting power, to-

gether with freedom of pouring through them the liquids used; and alsopresenting great facility of cleaning from any acciden- In claiming theabove, I

do not claim protecting such orifices with wire gauze, perforated metal,cylinders or chambers, packages or masses of shot, pumice stone, ormasses of tan- Witnesses:

B. V. (101', E. WOODWARD.

WILLIAM PRATT.

